I don't know what you mean by reasonably priced restaurant but I can recommend the Zeughauskeller. It is atmospheric and tasty. You can see the menu in English with Swiss prices at their web site. http://www.zeughauskeller.ch/index.htm
Wikitravel.org is a good place to begin your search for restaurants in Zurich. My family was always pleased with the food offered in the Manora restaurants throughout Switzerland. These are located in the Manor department stores. We especially liked the rooftop dining in Lucern's Manora. While this is definitely not elegant dining, it is very good local fare which is very reasonable. Happy Travels!
Second Henry's Zueghauskeller recommendation. If you get the daily "tagesteller" it can be quite reasonable, and very good. This past May we had outstanding New Zealand lamb, scalloped potatoes and fresh veggies! We were hankering for some good Swiss fare, but the price trumped the menu choice.
The best way to control the price of meals in Zurich is to frequent the department store restaurants. They are fabulous. Jelmoli, Globus, Manor, etc. Scope them out, and you will be suprised. Frankly, we have nothing like them in the U.S. There are various stations where the food is prepared. A grill for meat, individually prepared pasta, a salad bar to end all, hot veggie bars, fruit, pastries, bread, soup, etc. The "control" part is up to you, as you can get carried away in these venues.
There are many sidewalk takeaway offerings at Coop, and the formentioned department stores. You will see this is quite popular with the locals. So many benches surrounding the area provides a nice "people watching" experience.